Air separator



Feb. 11, 1936. T, J. STURTEVANT 2,030,612

AIR SEPARATOR Filed May 3, 1934 4 Sheets-Sheet l 9 nw ENrOR 79 0014: ISZ'Zu-zmf ORNEY Feb. 11, 1936. J STURTEVANLT 2,030,612

. A IR SEPARATOR Filed Ma a; 1954 4 Sheets-Shee t 2 ATT RNE) Feb. 11, 1936.

T. J. STURTEVANT' 2,030,612 w AIR SEPARATOR Filed May 3, 1934 4 Sheets-Sheet 3 IN VE NTOR flomus I szarmnf.

BY M

A7 RNEY 1 Y T. J. STURTEVANT 2,030,612

AIR SEPARATOR Filed May 5, 1954 4 Sheets-Sheet 4 fM/E/VTOR 75022145 fsfzzrfamnf 681 5r 1 1 939 ATT RNEY patented Feb. 1 1 i936 iTED STATES PATENT OFFICE SEPARATOii Z Application May 3, 1934, Serial No. 723,749

12 Claims.

This invention relates to air separators of the whirlwind type for sizing or grading material, the general principles of which are well known inthis art. As disclosed in prior United States patents, for example, T. J. Sturtevant No. 1,769,-

721 dated July 1, 1930, a separating chamber and a surrounding collecting chamber are in communication through upper and lower openings, a fan above the upper opening causing the air to circulate upwardly through the separating chamber and downwardly through the collecting chamber in a closed circuit. The material to be graded is introduced into the separating chamber and centrifugally into the path of the rising air current. The fines, or that part of the material that can be lifted and flow through rejective means located between the zone of distribution and the upper or outlet opening of the separating chamber, pass to the collecting chamber to be delivered through an outer cone to a fine outlet while the tailings, or heavier particles, gravitate downward past the lower or inlet opening of the separating chamber and are delivered through an inner cone to a tailings outlet.

I The principal object of this invention is to increasethe efiiciency and to improve the selective action of the separator or to provide forvarying the size of the finished product througha wide range. To this end a feature of the invention comprises a powerful centrifugal rejector fan or deflector, located just under the outlet opening of the'separating chamber and lying across the stream of air passing to said opening, having provision for adjustment to vary the rejective and defiective effect of its moving blades.

The range or flexibility of the separator may be widened by a judicious variation in the lateral position of the blades of the circulating fan in combination with the adjustable rejector fan at the under side of the outlet through which the circulating fans draws the air stream for recirculation.

It has been found that a certain amount of dust returns with the air that enters the separating chamber through the inlet opening. This dust should-move upward with the air and not drop downward to mingle with the tailings. If a strong whirl of the air is permitted in the zone .above the inlet opening, there is a tendency to .make a centrifugal collector of the tailings cone so that any fine dust which may re-enter the separating chamber does not return upward with ,the returned air, as it should, to pass again to the collecting chamber.

A further object ofthe invention is to control,

more or less, the whirl of the air within the separating chamber below the zone of distribution of the material to be graded, this is, below the distributor plate and above the inlet opening. To this end, in the preferred form of the invention, such ribs or projections as would give fanning action to the distributor plate are eliminated as far as possible, and its diameter may efiiciently be less than that of its bailie plate which screens the outlet opening. The variable whirl-producing rejector fan. preferably is extended well across the classifying zone of the separating chamber so that, when acting in combination with a distributor plate constructed to impart a minimum air disturbance as it rotates, there will be a maximum centrifugal action in. the zone below the outlet opening and a minimum centrifugal action in the zone above the inlet opening, a condition which favors efficient action of the separator as a whole.

Further refinements and improvements relate to special forms of blade for the rejector fan, and to special forms of support for the circular series of blades composing the fan.

To the accomplishment of these objects and such others as may hereinafter appear, as will readily be understood by those skilled in the art, the invention comprises the features and combinations of parts hereinafter described in detail and then pointed out in their true scope in the appended claims.

The nature and scope of the invention will be understood from a description of the preferred embodiment and modifications thereof illustrated in the accompanying drawings, in which:

Figure lis a view, in vertical section, through an air separator of the whirlwind type provided with the preferred form of the improved features herein claimed;

Fig. 2 is a View, in plan, of the centrifugal rejector fan as indicated by the line 2--2 of Fig. 1;

Figs. 3 and 4 are views, in plan and in end elevation respectively, of one of the adjustable fan blades of the rejector fan shown in Fig. 1;

Fig. 5 is a view, in perspective, of the said fan blade;

Fig. 6 is a view, in plan, of a modified form of the centrifugal rejector fan providing for a change in diameter;

Fig. '7 is a view showing a fragment of the edge of the structure shown in Fig. 6 at the lap joint of the removable fan-bearing annulus;

Fig. 8 is a view, in plan, of the structure shown in Fig. 6 with the annulus removed and the fan blades remounted on the baflie plate;

1 collecting chamber 32.

Fig. 9 is a view showing a fragment of the edge of the structure shown in Fig. 8 at the lap joint of the bafile segments;

Figs. 10 and 11 are fragmentary views, in sectional elevation, showing the relation of the fan blades, of the two rejector fan structures shown in Figs. 6 and 8, to the cover plate of the separating chamber;

Fig. 12' is a view in perspective of a modified rejector fan blade; and

Figs. 13 and 14 are views, in section, on the lines 53-43 and Hl-M respectively of Fig. 6..

Referring more particularly to Fig. l of the drawings, the whirlwind type of separator therein shown comprises an outer casing I consisting of a drum having a cylindrical wall 3 closed by a fiat head 5, and having a cone 1 at the lower end thereof terminating in a discharge spout 9. Within and spaced from the outer casing is an inner casing or drum l l consisting of a cylindrical wall it covered by a fiat head l5 with a centralized outlet opening ll therein, and having a conical shell it at the lower end thereof. This inner casing is supported by brackets 2| between and secured to the walls 3 and I3.

Beneath and spaced from the conical shell i9 is a cone 23 provided with a discharge spout 25 which extends laterally through an opening in the cone l of the outer casing. The cone 23 is supported by plate struts 21 between and secured to it and the cone 1.

The inner casing forms the separating chamber 353, and the annular space between the inner and outer casing Walls 3 and I3 forms the settling or The space between the conical shell l9 and the cone 23 serves as an inlet opening for the passage of air from the settling chamber back into the separating chamber. Lo-

.cated at this inlet is a series of adjustable vanes 33 pivotally connected to a ring 34 secured to and projecting outward fromthe lower edge of the conical shell l9 and adjusted by a hand wheel all substantially as shown and described in United States patent to T. J. Sturtevant No. 1,788,361, January 6, 1931.

The materials to be graded are delivered to the separating chamber through an inclined delivery chute 35 and through a conical feed hopper 36 depending from the head 5 and having a lower cylindrical neck 31 extending down centrally through the circular outlet opening in the head E5 of the separating chamber.

Mounted on the head of the outer casing are a pair of channels 38 supporting a housing 4!] which extends downward through the casing head 5 into the hopper 36 and has bearings at'the; upper and lower ends thereof. A vertical driven shaft 4| is journalled in said bearings and, within the portion of the housing above the head 5, has a bevel gear 42 fast thereon meshing with a bevel pinion 43 on a horizontal driving shaft 44 journalled in an inner bearing carried by the housing 4!! and in an outer bearing 45 carried by a transverse channel 45 bridging the channels 33. At the outer end of the driving shaft 44 is a pulley 4'! which may be driven from any suitable source of power.

The driven shaft 4| extends down from its bearing housing centrally of the feed hopper 36-3'l, its lower end projecting therefrom into the separating chamber 30. This lower end carries a distributor comprising a plate hub 45! and a plurality of segmental plates 59, secured to the plate very little air disturbance as it rotates at the lower limits of the classifying zone.

Projecting up from the margin of the distributor plate hub 49 are posts 5| carrying a cylindrical hub 52 surrounding the cylindrical neck 31 of the feed hopper and provided with a lower horizontal flange 53 and an upper cone flange 54. Secured to the cone fiange 54 are a plurality of oblique arms 55 each carrying 'a circulating fan blade 56. The fan rotates clockwise in a chamber 60 between the casing heads 5 and I5 and its blades 56 may be radially adjusted on the supporting arms 55 by the provision of several parallel rows of bolt holes. In Fig. l the blades'are shown as bolted on through the central one of three oblique rows of bolt holes which secures the blades in their median radial position. By

bolting through the two holes of the upper row chamber casing. This bafile, which supports the novel rejector fan blades of this invention at its upper side, may take one of several specific forms, for example, as illustrated by Figs. 2, 6 and 8.

Referring to Fig. 2 and the details of Figs. 3 to 5, the distributor baffle 65 in one embodiment of the invention may conveniently be formed of six segmental sections 66 secured at their radial meeting edges in any convenient or usual manner as by flange bars 68 welded along these edges at the upper faces of the segments and punched to be bolted together. The flange bars 68 are somewhat less in length than the radial dimension of the bafile leaving an uninterrupted or planate margin for mounting a marginal series of rejector fan blades it. The planate margin of the baflle is pierced by a series of regularly spaced holes H (Figs. 3 and 4) each adapted to receive the pivot 12' (Figs. 4 and 5) which may be abolt passed through a blade steadying or base-plate 14 conveniently in the shape of a disc which serves as a turn-table and preferably is of such diameter that it will not overlap the edge of the bafile when welding at the meeting joint and over the bolt head M which may be slotted to receive the blade if desired. The blades 10 are of greater length than the diameter of a disc 14 and preferably though not necessarily are secured with the rear or inner edge thereof substantially flush with the edge of the disk. The drawings illustrate by full lines this normal setting of the blades 10 in which position they are radial and project sufliciently beyond the edge of the baflie to lap under the cover plate l5 (see Figs. 1 and 5). The swivelling of the base plates on the baflle providesfor setting the blades at any desired angle to the normal (full line) position (see Fig. 3), or even in a completely reversed position to bring their outer edges at or within the edge of the baflie according to their relative setting on the base-plate. The base-plates may be secured to the baflle 65 for any angular adjusted position of the blades by clamps 15 bolted to the baflle plate between adjacent base-plates and long enough for their ends to overlap the base-plates. Considering the rejector fan as having a clockwise direction of rotation a forward angle of blade adjustment is shown by the dotted lines at the left in Fig. 3 and a backward angle of rotation is shown by the dotted lines at the right in Fig. 3. This would be reversed if the direction of rotation is contraclockwise. The advantage gained by the swivelling blade mounting will presently be described.

A modified form of a baifle rejector fan is illustrated by Figs. 6 and 8. Here the joined baille segments Sfil produce a circular plate of slightly smaller diameter than as shown in Fig. 2 and a planate margin for supporting the rejector fan blades Till may be provided by the addition of an annular plate removably bolted to the ballle at its outer edge. In order to facilitate removal for a reason presently to be made clear, the annular plate is formed of several segmental pieces 16, edge-butted and held from buckling at the joints by upper lap plates Tl (Figs. 7 and 14). There is a considerable overlap of the segments 16 at the margins of the baffle segments 66 i the flange bars 63! being shortened to permit this. The remaining butted edges of the segments 66l are provided with under lap plates '19 (Figs. 9 and 13) for rigidity. The lap plates l! and 19 may be bolted to one segment and welded to the other. The annulus is provided with an outer and an inner circular series of bolt holes, and the bailie is provided with a single annular series of bolt holes that match with the inner series of the annulus. Bolts and nuts (Fig. 10) at these matching holes removably secure the two plates together. As thus erected the bafiie has substantially the same diameter as the preferred baille 65 illustrated by Fig. 2.

Each fan blade Elli may be mounted for angular adjustment on a vertical pivot, to be set in one of the outer series of bolt holes in the removable annulus, by the means illustrated in Fig. 10. As there shown the blade has a recess 82 cut in its lower edge for receiving the head of a threaded bolt 84 the shank of which passes through a hole in a base-plate ii i, and the blade may be secured to the base-plate by welding as before. A nut 85 on the bolt is turned up to hold the blade at any desired angle of adjustment.

It will be observed that for each bolt hole in which a fan blade is seated there is a corresponding bolt hole in the margin of the baffle plate. Thus the size of the centrifugal rejector fan may be varied by taking out the bolts 80, removing the annulus 76 from the segment baflie 661 and then re-securing the fan blades by their own bolts and nuts in the series of bolt holes at the planate margin of the bafile. The result of this change is shown by Figs. 8 and 11.

The invention is not limited to the use of flat plate fan blades. For very fine products blades of the shape and form shown in Fig. 12 may be used. Here the inner oblique end of a blade 102 is provided with a projecting flange overhanging the impact face and the short upper edge of the illustrated blade may also have a similar flange 92. If desired, this blade may be rectangular as in Fig. 5 and the inner end or both the top edge and inner end may be provided with flanges at the impact face. The direction of rotation is indicated by the arrow, Fig. 12. Thus the flanges tend to prevent material in contact with the blade from passing to the outlet opening.

In any form of the rejector fan a height of blade is provided that will just sweep by the stiffening ring at the outer edge of the outlet opening l1. Some variation in the height of the blades may be required should the blade supporting margin of the baffle not lie in a plane parallel to that of the casing cover plate l5.

Those skilled in the art will recognize the advantages gained by a separator having the flexibility of construction hereinabove described. The effect of the circulating fan may be varied by shifting its blades inward or outward. The rejector fan may be varied in size and may have any number of blades desired and of any shape desired. The rejector fan blades may be set at either a forward angle to produce a coarser prodnot or at a backward angle which causes the blades to reject more material and thus produce a finer product. The radially set blades will produce a separated product of an intermediate fineness. The blades may project well toward the wall of the separating chamber or may be wholly above the ballle support.

It will be observed that the rejector fan operates as close as is mechanically possible to the outlet of the separating chamber. For simplicity and convenience this fan is mounted on the distributor bafile although it may be a separate device. By just sweeping the under side of the cover plate surrounding the outlet there is little chance of the unseparated material passing over the fan and thus to the collecting chamber. The fan blades, extending, as preferred, to sweep a circle larger than the outlet opening, keep the dust laden air in the classifying zone. violently whirled and act to deflect, bat or centrifuge the oversize particles outward or to the covered corner of the separating chamber where they drop down, while permitting the fines to pass through the fan and thus to the outlet to be lifted by the circulating fan. Thus centrifugal selective action is continual. As hereinbefore stated the defiective or rejective action can be varied through a wide range by due selection of the inclination which these faces of the fan blades are to have with respect to a radial position.

The nature and scope of the present invention having been indicated and its preferred embodiments having been specifically described, what is claimed as new, is:

1. In an air separator of the type described, the combination with a circulating fan for causing air currents to flow upward through a top outlet of a classification zone and a rotary distributor in the lower part of said zone, of a rotary rejector fan between the distributing plate and circulating fan comprising a support having a circular series of rejective fan blades each of said fan blades being adjustable on a vertical axis to turn the faces of the blades at an angle forward or backward from a radius in regard to the direction of rotation thereby to vary the rejective effect, and means for securing said blades in any selected position either radial or oblique to radial.

2. The air separator described by claim 1 in which each rejector fan blade is individually adjustable and is separately secured in its selected position.

3. The air separator described by claim 1 in which the support for the rejective fan blades consists of an imperforate plate below and baffling said top outlet.

4. In an air separator of the type described, the combination with a covered casing defining a zone of classification and having an outlet opening through its cover; a circulating fan for causing an air stream to flow upward within said casing and through said outlet and a rotary distributor for delivering the material to be classified into said rising air stream, of a rotary rejector fan located well above said distributor having a series of vertically set blades the upper edges of which sweep substantially in the plane of said outlet, said rejector fan blades being 6. In an air separator of the type described,

the combination with a covered casing defining a zone of classification and having a centralized outlet through its cover, a circulating fan for causing an air stream to flow upward within said casing and through said outlet, a baffle plate below said outlet and means below said baffle plate for distributing material into said air stream, of a series of rejective fan blades at the margin of said baffie plate, each blade being mounted on a vertical pivot pin with its face normal to the plane of the baffle plate, and means for setting said blades in a radial or oblique to radial position as desired to regulate the size of the material to be carried in the air stream through said outlet.

7. The air separator described by claim 6 in which the pivot pin is so related to the edge of the baliie and to the ends of the blade that in one radial setting the blades all project beyond the edge of the baflle plate while when turned 90 to a reversed radial setting the blades do not so project.

8. The air separator described by claim 6 in which each blade is secured to a steadying plate or turn-table and said pivot pin projects from the lower face of said turn-table and seats in a hole in the baflie plate.

, 9. In an air separator of the type described having a rotary shaft within the separating chamber, a distributor including a baflie cover plate rotated by said shaft, and a series of rejective fan blades at the margin of said distributor cover plate, each set vertically and each ing and rejector fans to regulate the size of the material selected and drawn through the outlet comprising means for varying the relation of the blades of the circulating fan to the outlet and means for varying the rejective the rejective'and deflective action of the blades of the rejector fan on the material in the air stream attempting to pass through said rejector fan to the outlet.

11. The air separator described by claim 10 in which the circulating fan blades are adjustable radially to increase or decrease the diameter of said fan and in which the rejector fan blades are adjustable angularly on a vertical axis to increase or decrease the centrifugal action on the material flowing inward through the rejector fan and impinged bylits blades. 7 12. A rejector fan to be positioned within the separating chamber of an air separator of the class described and in the inward path of the dust laden air comprising a baffle plate, a series of blades mounted at the margin of said baffle each individually adjustable by rotation on a vertical axis to vary the outside diameter of the circle swept by said fan blades.

' THOMAS J. STURTEVANT. 

